Electronic circuitry for applications such as signal processing, computing, and telephony often includes circuit boards that are densely populated with heat-generating components. The passive or active removal of excess heat from the environment of such circuit boards is often necessary to assure the proper operation of the circuitry.
Forced convection is a widely used active method of heat removal. In typical applications, circuit boards are stacked in parallel fashion within an enclosure, and fans are used to force air to flow, in a direction parallel to the faces of the boards through the gaps between successive boards.
Such an approach is most useful when the heat sources are uniformly distributed across the face of each circuit board. However, it is becoming increasingly common to design circuit boards in which an isolated hot spot, corresponding for example to a high-speed processor or a high-power component, generates substantially more heat per unit area than is average for the circuit board on which it is mounted.
There remains a need for more effective targeted cooling of such isolated hot spots.